ENH: Applying patch from bug#3443 to implement FindwxWidgets.cmake properly.  It also updates the UseWX test and WXDialog sources to use the new find script.

BUG: If the user specifies a cache entry on the command line without a type, the FIND_* commands should add the type and docstring to the given value and put it back in the cache.

STYLE: Added note about singular versus plural name for XXX_INCLUDE_DIRS.  Added XXX_LIBRARY_DIRS and XXX_YY_INCLUDE_DIR conventions.

BUG: When handing the child stdin pipe a file, allow another process to be writing to the file at the same time.  This allows children such as tail -f to function properly.